1. Field of the Invention
The present invention relates to dispenser packages for flowable products and the like and, more specifically, to a new and improved configuration and structure of a stress concentrator aperture-forming member for containers and dispenser packages which contain and dispense a quantity of flowable product, having particularly advantageous application to single use containers and packages.
2. Description of the Prior Art
Various attempts have heretofore been made to provide a dispenser package into which a flowable product may be packaged in the quantity normally required for a single use, and from which such flowable material may be dispensed.
One type of package is a pillow pouch or sachet, typically made of relatively thin plastics/and foils or combinations of laminated plastics and foils. These packages are most frequently encountered as containers for catsup, mustard, other condiments, homecare preparations such as hair conditioners, dyes and cremes, et al. Although this type of package is universally used, it is also universally disliked by the consumer. In order to access the contents, the pouch must be held in one hand while a tearing motion and force are applied by the other hand. Creating the initial tear to break the envelope's seal is often very difficult. Moreover, once the initial tear is created, the laminated foil and/or plastic material not only often tears in an uncontrolled fashion, but the holding pressure exerted by one of the user's hands often forces the contents out of the envelope not only before the user is ready to apply the contents but even before the tearing motion is complete. Opening is generally so difficult that the pouch must often be opened by biting. Opening these packages has led to frayed tempers, broken fingernails, and chipped teeth to name a few of the many problems. A further disadvantage is the fact that the user must use both hands to open the container. In the case of invalids, arthritis sufferers and other handicapped people, opening these packages is virtually impossible.
Another package is the peel top cup used for butter, margarine, syrup, sauces, salad dressing, etc. This package also requires good eyesight, manual dexterity, and two hands to open. Similar packages for coffee creamers and the like suffer the same difficulties enumerated above with the pouch or sachet. Indeed, many people cannot open them.
Another type of package is the unsealed paper corrugated package used for salt and/or pepper, which upon bending along a cut through line across the corrugations forms a hole through which the salt or other solid materials contained in the corrugations may flow. These salt packages usually have polyethylene liners which do not rupture or collapse as in the present invention. Also, these packages only dispense dry, solid flowables with the assistance of gravity, and cannot adequately dispense "wet" or liquid flowables nor even contain them as in the present invention, which utilizes hydraulic or compressive forces to direct the stored liquids out of the container.
Redmond's own U.S. Pat. No. 3,986,640 (hereinafter the '640 patent) discloses a dispenser package which represents a marked improvement over the opening difficulties of the foregoing prior package structures in that it accomplishes efficient dispensing of a predetermined quantity of the contents with a one-handed motion and without presenting the opening difficulties previously associated with opening by removal of a cover or tearing of an envelope or pouch. In the '640 patent, the flowable product is contained within a pouch defined by a flexible sheet material and a sheet of relatively stiff material, which has a predetermined fault line or cut pattern scored into the stiff material such that the stiff material will rupture on the fault line when stress is placed upon the sheet of stiff material. Bending the above sheets into a "V" shape ruptures the fault line or cut pattern, which is located in the vertex of the angles formed by the sides of the "V" and creates at least one opening through which the flowable substance is forced upon compression of the flexible pouch by the relatively stiff sides of the "V" as they are brought together. Advantageously, one motion with one hand suffices to open and efficiently dispense the product contained.
The Redmond et al. U.S. Pat. No. 4,493,574 (hereinafter the '574 patent) discloses a dispenser package similar to that of the Redmond '640 patent, but which includes the use of at least one stress concentrator protrusion member displacing at least a portion of the fault line or fault pattern out of the plane of the relatively stiff member. The preferred embodiment of the protrusion member there disclosed has a substantially pyramidal shape which displaces the fault across the apex thereof and is substantially symmetrical with respect to the fault line. The purpose of the stress concentrating protrusion member is to, upon bending into a "V" concentrate stresses at the fault line causing the protrusions to rupture at the locus of the fault line, creating an aperture through which flowable product is dispensed.
The structure of the '640 and '574 patents have been and continue to be commercially successful. However, it was found that in the package configurations therein disclosed, depending upon the particular flowable material enclosed, application of bending pressure could cause a small amount of enclosed material to squirt or "spit" out of the opening at the instant of rupture of the fault line. Redmond U.S. Pat. No. 4,611,715 (hereinafter the '715 patent) substantially reduced this potential squirting problem by providing a shallow channel directly behind the fault line which connects two spaced pockets located on either side of the fault line.
The Redmond U.S. Pat. No. 4,724,982 (hereinafter the '982 patent) also discloses a dispenser package structure similar to the other aforesaid Redmond patents and, in addition, discloses the use of at least one asymmetric substantially pyramidally shaped stress concentrator, which is particularly advantageous where it is desired to simultaneously dispense two different products from isolated chambers.
While the above dispenser packages offer many advantages over prior packaging systems, the above packages nonetheless have certain disadvantages. Although superior to prior pouch style packages and preferred by consumers, the above packages may cost more than the prior pouch packages due to various stiffness and barrier requirements and materials costs. Additionally, because the pyramidally-shaped stress concentrator members protrude outwardly from the surface of the enclosed dispenser package, additional care was needed in packing, stacking, and shipping to prevent inadvertent damage which, although infrequent, caused some dispenser packages to become deformed or even opened prior to use.